Enhanced activity and stability of Chromobacterium viscosum lipase in AOT reverse micellar systems by pretreatment with acetone

The activation and stabilization of Chromobacterium viscosum lipase (glycerol-ester hydrolase, EC 3.1.1.3) by a simple pretreatment with acetone was studied in AOT/water/isooctane reverse micellar systems, using the hydrolysis of olive oil as a model reaction. The maximum activity of acetone treated lipase was found to be 160% higher than that of native lipase. These observations were rationalized by the assumption based on the lipase conformational changes accompanied by the enhancement of lipase surface with hydrophobic amino acids. The dependence of catalytic activity on the various parameters relevant to the pretreatment procedure such as acetone content, the pH of water-acetone solution, agitation time of the lipase in water-acetone solution and freeze-drying time were investigated. The change in lipase conformation due to the treatment with acetone was confirmed by typtophyl fluorescence spectroscopy as well as lipase microencapsulation methods in reverse micelles. The acetone treated lipase entrapped in AOT reverse micelles was very stable, retaining over 83% of its initial activity after 40 days, whereas the half-life of native lipase was 38 days.